1. Field of the Invention
The invention relates to eyewear. More specifically, the invention relates to clip-on attachment lenses for eyeglasses. Such clip-ons are typically shades that convert regular eyeglasses to sunglasses.
2. Description of the Related Art
Clip-on lenses are currently very popular. The prior art knows such clip-ons that are held mechanically on the conventional eyeglasses with clip brackets, for example. Newer clip-on designs allow the attachment to be held on the regular eyeglass frame by way of magnets.
U.S. Pat. No. 6,149,269 to Madison, for example, discloses an assembly wherein a magnet is incorporated in a lateral end piece of an eyeglass frame. The lateral end piece is the structure at which a temple piece is attached, typically in articulating fashion. Madison discloses a variety of attachment mechanisms, each present in a variety of combinations. In one embodiment, for instance, the magnetic holding force provided by the magnets in the end pieces of the eyeglass frame and the clip-on frame respectively, is augmented by a mechanical locking force provided by a bracket which retains the clip-ons on the eyeglass frame. The bracket is attached to the clip-on above the magnetic lateral extension and, when the clip-on is placed on the eyeglasses, the bracket reaches behind the end piece of the eyeglass frame.
U.S. Pat. No. 6,132,040 to Xiao discloses a similar system in which a magnet is incorporated in each lateral end piece on the frame of the eyeglasses and of the clip-ons. The end pieces of the two frames are configured such that, upon being placed in position, the end pieces of the clip-ons reach behind the respective end pieces of the eyeglass frame to hold the clip-on in place with the magnetic force provided by the magnets and with a mechanical force provided by the end pieces.
U.S. Pat. No. 6,139,142 to Zelman discloses a similar structure. In one embodiment, the patent discloses an assembly in which the magnets are incorporated in the bridges of the eyeglass frame and the clip-on frame, respectively. In addition, the clip-on is provided with top brackets which hold the clip-on frames in place on the eyeglasses.
These foregoing disclosures are representative of the state of the art in which the eyeglasses and the clip-on attachments have a full frame. Some modern designs of eyeglasses, however, do not have a full frame. In frameless eyeglasses, the lenses are held in place only by the bridge. The lateral end pieces, and the articulated temple pieces, are laterally attached to the eyeglass lenses without a direct attachment to the bridge, i.e., the bridge and the end pieces are connected only via the lenses themselves. In so-called half-frames, the bridge is connected to the lateral end pieces via an upper frame. Clip-ons for frameless eyewear require only the bridge to hold the two lenses to one another. In this context, it has not been possible to provide magnetic clip-ons for frameless eyeglasses, that is for clip-ons which do not have a frame.
Also, the prior art systems are quite bulky and they require proper alignment of the mechanical and magnetic attachment members. In other words, when the clip-ons or the eyeglass frames are only slightly bent, their easy and secure attachment is no longer assured.